A MT 2D modelling of the Apenninic margin and Bradanic trough after identification of an artificial e.m. wide-band source on the natural MT data

Abstract

In the frame of Italian research project «CROP», a magnetotelluric (MT) survey was carried out in Southern Italy, above the Apulian platform, with the aim to investigate its transition beneath the Apennine chain. The MT stations were divided into two areas, the first around Lavello town, the second south of Mount Vulture inactive volcano. The standard processing of MT raw data, collected with the single-site scheme, gave fairly non-plane wave response as concerns data of Lavello area, while the volcano's area data were compatible with a natural plane-wave e.m. field response. The Lavello area results were shown to be heavily affected by a near field effect of a strong wide-band electromagnetic source located several kilometers NE of Lavello. After the identification of this effect and an attempt to interpret these data, a 2D interpretation of the whole survey was then possible and the main result can be summarized as follows: a) the «electrical» boundary of the Bradanic trough should be displaced about 4 km toward SW; b) in the area south of Melfi town, the carbonatic platform should lie at a depth of about 8 km.